X.400 and SMTP : battle of the E-Mail protocols

Ch. 1. Introduction -- Ch. 2. Networking -- Ch. 3. Message Structure -- Ch. 4. Backbone Topology -- Ch. 5. Message Transfer -- Ch. 6. Directory Service -- Ch. 7. Security -- Ch. 8. Heterogeneous Mail Networks -- Ch. 9. Summing It Up -- App. A. OSI Implementation -- App. B. X.400 Example -- App. C. MIME Example -- App. D. POP3 Example -- App. E. SMTP Header -- App. F. MAILbus 400 Architecture